Background: To investigate the rapid increase in incidence of type 1 diabetes mellitus (T1DM) in children <5 yr in Austria.
Methods: Data of children born between 1989 and 2005 (n = 444) from the T1DM children incidence registry were linked with birth certificates (n = 1 407 829).
Results: Age of mother, level of education, birth weight, birth length, body mass index, and APGAR score at 10 min were not significant. Boys have about 25% higher risk than girls [hazard ratio = 0.75, 95% confidence interval (CI): 0.62-0.91]. The risk of developing diabetes increases over time significantly (1989-1991 vs. 2001-2005, hazard ratio = 2.86, 95% CI: 2.07-3.94). The linear effect of parity is borderline significant (p = 0.045), with lower risks for second and later born siblings. Marital status is significant [hazard ratio = 0.73, 95% CI: 0.57-0.90)]. Native-born children exhibit twice as high risk as non-native children (hazard ratio = 0.51, 95% CI: 0.37-0.71). Birth weight shows a positive but not significant effect on risk of T1DM.
Conclusions: In this very young and rapidly increasing cohort of diabetic children <5 yr of age, no association with birth weight but with year of birth, gestational age, nationality and parity could be observed.